R Rating Insulation Attic

An insulating material s resistance to conductive heat flow is measured or rated in terms of its thermal resistance or r value the higher the r value the greater the insulating effectiveness.

R rating insulation attic.

In general an attic s r value should be between r 30 and r 49. Recommended insulation levels for retrofitting existing wood framed buildings. In particularly cold climates you might go up to r 60. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7.

While some ceilings in the southwestern part of the united states require a minimum of r 19 insulation most attics or ceiling areas require a minimum of r 38 in the ceiling. R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. As a benchmark one inch of solid wood has an r value of 1. Add insulation to attic.

Existing 3 4 inches of insulation. First things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation. See the department of energy s doe ranges for recommended levels of insulation below. Houses in a cold climate should have a minimum of r 49 in the attic which is equivalent to approximately 16 of fiberglass insulation.

The r value depends on the type of insulation its thickness and its density. R value insulation chart find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. Warmer climates only require an r 38 or higher or about 12 or more. The r value for cellulose insulation in an attic depends on several factors including the size shape and construction of your attic typical weather conditions where you live any air leaks and.

Let s say the insulation you ve selected has an r value of three per inch and. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces.